Varicose Veins Possess Greater Quantities of MMP-1 Than Normal Veins and Demonstrate Regional Variation in MMP-1 and MMP-13

Abstract

Background. Studies have reported that structural proteins such as elastin and collagen are decreased in varicose veins compared to normal controls. We hypothesized that the changes observed in varicose vein wall composition may be related to alterations in extracellular matrix remodeling proteins, such as the matrix metalloproteases and serine proteases. In addition we hypothesized that there may be regional variation in the expression of these enzymes within the leg. Patients and materials. One-centimeter segments of the proximal and distal greater saphenous vein (GSV) were obtained from patients undergoing ligation and stripping for venous insufficiency (vv) ( n = 15) or GSV harvest in conjunction with coronary artery bypass grafting (CABG) ( n = 7). All vv patients had incompetence of the GSV by color flow duplex. Vein specimens were examined for MMP-1, 3, and 13, tryptase, and GAPDH mRNA using semiquantitative RT–PCR analysis. Quantification of MMP-1 and 13 (active/latent forms) and tryptase was performed using Western blot analysis. Western blots were analyzed using scanning densitometry and standardized to normal controls and values expressed as the median densitometric index (D.I.). Nonparametric statistical methods (Wilcoxan signed rank test and Mann–Whitney U test) were used for analysis. Results. We were able to amplify MMP-1, MMP-13, and tryptase mRNA from both proximal and distal segments of all greater saphenous veins studied. MMP-3 mRNA, however, was not found in either segment of any of the veins examined. A semiquantitative analysis of RT–PCR products comparing the ratio of MMP-1, MMP-13, or tryptase mRNA to GAPDH mRNA showed no difference between cases and controls nor proximal vs distal vein segments. Western blot analysis revealed larger quantities of MMP-1 in varicose veins than in nondiseased veins from CABG patients (48.0 ± 36.7 D.I. vs 12.5 ± 6.8 D.I., P = 0.036). Investigation into the regional variation of proteases revealed lower amounts of MMP-1 in distal than in proximal vein segments (37.9 ± 35.0 D.I. vs 44.1 ± 41.6 D.I., P = 0.01). Similarly, we found significantly less MMP-13 in distal segments of varicose veins than in proximal segments (152.8 ± 130.0 D.I. vs 206.7 ± 173.3 D.I., P = 0.006). Conclusions. This study found that MMP-1 protein is increased in varicose veins when compared to controls despite no differences in mRNA expression. In addition we found that there is regional variation of MMP-1 and MMP-13 in diseased varicose veins. Lower leg veins have significantly reduced amounts of these proteolytic enzymes when compared to veins of the upper thigh. These data suggest that posttranscriptional regulatory controls could be responsible for the observed differences.